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HID: core: Correctly handle ReportSize being zero

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commit bce1305c0ece3dc549663605e567655dd701752c upstream.

It appears that a ReportSize value of zero is legal, even if a bit
non-sensical. Most of the HID code seems to handle that gracefully,
except when computing the total size in bytes. When fed as input to
memset, this leads to some funky outcomes.

Detect the corner case and correctly compute the size.

Cc: stable@vger.kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Change-Id: I0e61ea8b763669affdff3b8788a5fc66a8b7fcd3
CVE-2020-0465
Signed-off-by: Kevin F. Haggerty <haggertk@lineageos.org>
This commit is contained in:
Marc Zyngier
2021-01-03 21:13:43 +01:00
committed by Francescodario Cuzzocrea
parent 5783abdda7
commit 3380a4e394
1 changed files with 13 additions and 2 deletions
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drivers/hid/hid-core.c
+13 -2
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@@ -1170,6 +1170,17 @@ static void hid_output_field(const struct hid_device *hid,
}
}
/*
* Compute the size of a report.
*/
static size_t hid_compute_report_size(struct hid_report *report)
{
if (report->size)
return ((report->size - 1) >> 3) + 1;
return 0;
}
/*
* Create a report.
*/
@@ -1181,7 +1192,7 @@ void hid_output_report(struct hid_report *report, __u8 *data)
if (report->id > 0)
*data++ = report->id;
memset(data, 0, ((report->size - 1) >> 3) + 1);
memset(data, 0, hid_compute_report_size(report));
for (n = 0; n < report->maxfield; n++)
hid_output_field(report->device, report->field[n], data);
}
@@ -1256,7 +1267,7 @@ int hid_report_raw_event(struct hid_device *hid, int type, u8 *data, int size,
csize--;
}
rsize = ((report->size - 1) >> 3) + 1;
rsize = hid_compute_report_size(report);
if (rsize > HID_MAX_BUFFER_SIZE)
rsize = HID_MAX_BUFFER_SIZE;